It remind me of "Frukt" plus "Ost", i.e.. Fruit and Cheese in a good breakfast.
Haha :) for reference, it's derived from lower German "vrökost", where "vrö" means "early" (as does "früh" in modern German) and "kost" means "food" - which it still does in modern Swedish.
I always get those two confused but that's an awesome way to remember it! Have a lingot! :)
Do these words all end with either '-et' or '-en' or are there more endings?
I believe so, as the indefinite forms of nouns are either ett (like ett barn) or en (like en pojke) and generally you take the en or ett and stick it on the end of that word to make the definite form.